Grid-type resistor



Nov. 24, 1970 L. E. WEYENBERG 3,543,213

GRID-TYPE RESISTOR Filed Dec. 30, 1968 Jm/mlar a/ b 50 490716! ;f W ycnZW fi saw 5/26, M

3,543,213 GRID-TYPE RESISTOR Lionel E. Weyenherg, N34 W23575 Capital Drive Parkway, Pewaukee, Wis. 53186 Filed Dec. 30, 1968, Ser. No. 787,969 Int. Cl. H01c 3/00 US. Cl. 338-290 9 Claims ABSTRACT OF THE DISCLOSURE The invention relates to a grid-type resistor and more particularly to a grid-type resistor having an improved mounting construction.

In one common form of grid resistor, a series of cast or sheet metal grid strips are arranged in generally parallel relation and the ends of the adjacent strips are connected together in series. The grid strips are generally mounted on a pair of rods which extend through holes in the ends of the strips. With this type of mounting, insulated sleeves, spacers and washers are required in order to insulate the ends of the strips from the rods and to insulate the ends of the strips from adjacent strips. Therefore, this type of construction requires a considerable number of individual parts and correspondingly requires a substantial labor cost for assembly.

The present invention is directed to a grid-type resistor having a novel and simplified mounting construction. The resistor includes a series of generally parallel flat metal grids or strips having their ends connected together to provide the resistor with a sinuous or zig-zag configuration. The connected ends of the strips are received between interlocking insulating blocks and the edges of the blocks are mounted in channel shaped frame elements to provide an intergral assembly.

The grid strips can be similar in configuration to those shown in the US. "Pat. 3,212,045 of the same inventor, in which each grid strip is showed or bent in the same direction and the ends of adjacent strips are welded flatwise.

In a second form of the invention, the grid strip is an integral or one-piece metal band having a series of reverse bends to provide the sinuous configuration. In this form of the invention, portions of the strip located between United States Patent (315cc the reverse bends are secured between the insulating blocks to position and align the strip.

The resistor of the invention requires a lesser number of parts then conventional grid-type resistors with similar capacity. This results in a substantial saving in material cost as well as labor cost for assembly.

The resistor of the invention is an integral unit and a series of resistors can be readily mounted in a supporting frame in a manner so that each resistor can be individually removed and replaced if desired.

Other objects and advantages will appear in the course of the following description.

The drawings illustrate the best mode presently contemplated of carrying out the invention:

In the drawings:

FIG. 1 is a plan view of the grid-type resistor of the invention with parts broken away in section;

FIG. 2 is an end view of the resistor shown in FIG. '1;

FIG. 3 is a view similar to FIG. 2 showing a modified form of the mounting block construction;

3,543,213 Patented Nov. 24, 1970 FIG. 4 is a perspective view of a modified type of resistor of the invention; and

FIG. 5 is a sectional view of the resistor shown in FIG. 4.

FIGS. 1 and 2 illustrate a grid-type resistor including a pair of channel shaped end frames 1 which are connected together by tie-bars 2. The ends of the tie-bars 2 are provided with flanges having openings which receive studs 3, and nuts 4 are threaded on the studs 3.

A series of insulating blocks 5 formed of an electrically insulating material, such as ceramic, or the like, are located within the channel shaped end frames 1 and serve to support a series of generally parallel grid strips 6. As best shown in FIG. 2.

The grid strips 6 are similar in configuration to the grid strips shown in US. Pat. 3,212,045 of the same inventor, and generally each grid strip includes end sections 7 and 8 which are located in substantially parallel planes. The end section 7 of one grid strip is welded flatwise to the end section 8 of the next adjacent grid strip.

To offset or space the central portion of each grid strip from the central portion of adjacent grid strips, each strip is provided with a bent portion 9 which extends outwardly at an acute angle to the end section 7. In addition, each grid strip includes a pair of central sections 10 and 11 which are disposed at an angle to each other to provide a generally V-shape for the central portion of the grid strip. As the grid strips 6 are all bent or bowed in the same direction, any expansion of the strips under operating conditions will be in the same direction with the result that buckling of the strips will be eliminated and there will be no contact between adjacent strips under over-load conditions or vibrations.

Each block 5 is provided with a tongue or projection 12 which is received within a recess 13 formed in the end of an adjacent block to provide an interlocking relation for the blocks. The welded sections 7 and 8 of grid strips 6 are located within the recesses 13 and clamped between the bottom of the recess and the tongue 12, thereby preventing lateral displacement of the grid strips.

To prevent the grid strips from being pulled out of the recesses 13, each end section 7 of grid strip 6 is provided with a flange 14 which bears against the outer surface of the block 5.

Terminal strips 15 can be welded at any desired location to the grip strips 6, and as shown in FIGS. 1 and 2 terminal strips 15 are welded to the flatwise sections 7 and 8 and are provided with flanges 16 that bear against the inner surfaces of the blocks 5. Suitable electrical leads can be connected to the terminal strips.

To fabricate the resistor of the invention the ends 7 and 8 of the grid strips are welded together and subsequently the terminals 15 are welded to the grid strips. The welded ends 7 and 8 are then positioned within the recesses 13 in the blocks 5 and after the grid strips have been positioned with respect to the insulating blocks, the end frames 1 are connected together by the tie-bars 2 to complete the assembly.

The mounting construction of the invention substantially reduces the number of parts required over a conventional resistor of similar capacity. This results in a sub stantial savings in material cost and a corresponding reduction in the labor cost of assembly.

Identical grid strips 6 and insulating blocks 5 can be used for resistors of various wattage. By increasing the number of grid strips and blocks, the wattage can be changed as desired.

As a further advantage, the resistor is a modular unit and a number of the resistors can be slipped into a mounting frame. By removing or adding resistors to the mounting frame the overall capacity of the assembly can be readily varied.

FIG. 3 illustrates a modified form of the invention in which two resistors formed of interconnected grid strips 6 are supported by insulated blocks 17, similar to blocks of the first embodiment. Each block 17 is provided with a pair of projections or tongues 18 which are received adjacent blocks of each set, means for-preventing movewithin complementary recesses 19 in the end of adjacent blocks to provide an interlocking arrangement for the blocks. The welded end portions 7 and 8 of the grid strips are clamped between the bottoms of the recesses 19 and the corresponding tongues 18.

As in the case of the first embodiment, the side edges of the blocks are disposed within channel shaped end frames 20 which are connected together at their ends by tie-bars 21, similar to tie-bars 2 of the first embodiment.

The resistor shown in FIG. 3 is assembled in the same manner as that described with respect to the first embodiment except that two resistors, each composed of a series of grid strips 6 are supported by the blocks 17.

FIGS. 4 and 5 illustrate a second modified form of the invention. In this embodiment, the resistor includes a series of interlocked insulating blocks 22, similar to blocks 5 of the first embodiment, and the edges of the blocks are disposed within channel shaped end frames 23, similar to end frames 1, and the ends of frames 23 are connected together by tie bars 24.

A flat metal grid strip 25 having a sinuous configuration is clamped between adjacent blocks 22. The strip 25 includes a series of generally parallel central sections 26 which are clamped between the tongues 27 and the recesses 28 of the blocks. In addition, the grid strip is provided with a series of angular sections 29 which extend from the ends of each central section and terminate in reverse bends 30. Terminal strips 31 can be welded at any desired location to the grid strip 25.

Clamping the grid strip 25 between the blocks 22 firmly positions each turn of the grid strip and locks the grid strip against lateral movement. In addition, the angular sections 29 prevent the central sections 26 of the grid strip from moving longitudinally within the blocks, so that the grid strip is firmly anchored to the blocks in a manner in which both lateral and longitudinal movement are prevented.

The resistor of the invention is a modular type composed of a minimum number of parts that can be assembled in a manner to provide any desired wattage for the resistor. In addition, a series of resistors can be mounted in a supporting frame in a manner so that each resistor can be individually inserted and removed as desired.

I claim:

1. A gridetype resistor, comprising a first set of insulating blocks disposed in end-to-end relation, a second set of insulating blocks disposed in end-to-end relation and located in spaced relation with respect to said first set of blocks, an electrically conductive grid strip having a generally sinuous configuration comprising a series of grid elements extending between the sets of blocks and including end portions connecting the adjacent grid elements together, said end portions being clamped between ment of said end portions with respect to the blocks, and a pair of channel-shaped end frames associated with each set of blocks, the side edges of the blocks being received within the respective end frames to connect the blocks together in end-to-end relation.

2. The resistor of claim 1, wherein one end of each block is provided with a projection and the opposite end of each block is provided with a recess, said blocks being arranged so that a projection on one block is received within the recess in the next adjacent block to provide an interlocking relationship for said blocks.

3. The resistor of claim 2, wherein said grid strip is clamped between a projection on one block and a mating recess of the next adjacent block.

4. The resistor of claim 2, wherein said projection and said recesses are generally rectangular in shape.

5. The resistor of claim 1, wherein said grid strip is formed of a plurality of fiat sections and ends of adjacent section are connected flatwise together, said connected ends being clamped between said blocks.

6. The resistor of claim 5, and locking including means for preventing longitudinal movement of said ends with respect to said blocks.

7. The resistor of claim 6, wherein said locking means .comprises a flange connected to one of said end portions and located on the exterior of the blocks, whereby engagement of said flange with the exterior surface of said blocks prevents movement of said section.

8. A grid-type resistor, comprising a series of electrical- 1y insulating blocks disposed in end-to-end relation with each block having a pair of generally fiat faces, a pair of opposed sides and a pair of opposed ends, one end of each block being provided with a projection and the opposite ends of each block being provided with a recess, said blocks being arranged so that a projection on one block is received within the recess in the next adjacent block to provide an interlocking relationship for said blocks, and electrically-conductive grid strip having a generally sinuous configuration, spaced portions of said grid strip being clamped between a projection on one block and a mating recess on the next adjacent block, said grid strip extending laterally of said faces, a pair of channel-shaped end'frames to receive the respective sides of the blocks, and connecting means connecting the end frames together, said connecting means being located on the exterior of the blocks and disposed in engagement with the end blocks of said series to prevent displacement of said blocks from said blocks from said end frames.

9. The resistor of claim 8, and including means for preventing relative movement of the grid strip with respect to said blocks.

. References Cited UNITED STATES PATENTS 2,059,349 11/1936 Hertner 338-290X 3,212,045 10/1965 Weyenberg 338-3l6 'ELLIOT A. GOLDBERG, Primary Examiner US. Cl. X.R. 

